Garnaut update on climate science: avoiding high risks will require large changes

Ross Garnaut, the Australian government’s climate change adviser, today published the science update [PDF] to his 2008 report. It warns that recent research has “confirmed and strengthened” the view that the earth is warming and humanity is to blame. Temperatures and sea level continue to rise, and there are worrying signs that a 2ÂºC target may no longer be “safe”. Garnaut comments that it is an “awful reality” that his 2008 review did not overestimate the risks of climate change. Most telling, though, are the update’s final lines. After a section discussing scientific reticence as a possible reason (pace Hansen) why published science appears to systematically underestimate the extent and dangers of probable climate change, Garnaut states:

We should, however, be alert to the possibility that the reputable science in future will suggest that it is in Australiansâ€™ and humanityâ€™s interests to take much stronger and much more urgent action on climate change than might seem warranted from todayâ€™s peer-reviewed published literature. We have to be ready to adjust expectations and policy in response to changes in the wisdom from the mainstream science.

In other words, don’t bank on getting an easy ride. Full details below the fold.

Observations and research outcomes since 2008 have confirmed and strengthened the position that the mainstream science then held with a high level of certainty, that the Earth is warming and that human emissions of greenhouse gases are the primary cause.

By mainstream science I mean the overwhelming weight of authoritative opinion in the relevant disciplines, as expressed in peer reviewed publications.

The statistically significant warming trend has been confirmed by observations over recent years:

global temperatures continue to rise around the midpoints of the range of the projections of the Intergovernmental Panel on Climate Change (IPCC) and the presence of a warming trend has been confirmed;

the rate of sea level rise has accelerated and is tracking above the range suggested by the IPCC; and

rates of change in most observable responses of the physical and biological environment to global warming lie at or above expectations from the mainstream science.

It is an awful reality that no major developments in the science hold out realistic hope that the judgements of the 2008 Review erred in the direction of overestimating the risks of climate change.

The judgement of the Reviewâ€”that the greater risks of severe consequences under a scenario of 550 ppm concentrations of greenhouse gases make the extra mitigation cost to achieve a 450 ppm outcome worthwhileâ€”has been confirmed.

There is increasing discussion in the legitimate scientific literature of the possibility that large damage will occur at smaller increases in global average temperature than the IPCC focus and United Nations (Copenhagen and Cancun) agreement on holding temperature increase to 2ÂºC or less above pre-industrial level.

There is a case in managing the risks of climate change for seeking to reduce emissions concentrations below 450 ppm carbon dioxide equivalent, but that would first require a credible programme to get to 450 ppm.

Despite the increased scientific understanding of climate change, and confidence in the science’s conclusions about climate change, public confidence in the science seems to have weakened somewhat in Australia and some other countries since 2008.

The scientific community has given greater attention to the ‘emissions budget’ approach that was introduced in the 2008 Review to the global and national task of reducing emissions. This approach warns us that we are rapidly utilising the atmosphere’s remaining capacity to absorb greenhouse gases without generating high risks of dangerous climate changeâ€”and now face the challenge of absorbing more carbon dioxide from the atmosphere than we are adding from human activity.

The immediate implication is that avoiding high risks will require large changes in trajectories at an early date.

7 thoughts on “Garnaut update on climate science: avoiding high risks will require large changes”

Every scientific report gets worse. The Australian Government together with the USA and NZ ( and many more) make a lot of money through the carbon industries and can not quite grasp the reality that the party is over and it really is cheaper to make changes now rather than try to put things right when it is too late. With OZ being one of the biggest coal exporters in the World I watch with interest how they are going to solve the situation.

I fear they are going to dodge rather than solve the situation. Here in NZ Solid Energy is dead set on developing Southland lignite and the government is unlikely to stand in their way. Thay are also bidding to buy Pike River and hoping to mine it by a mixture of opencast and underground mining. Hide is all out for opencast. It’s apparently justification enough to mention the billions of dollars lying there waiting to be cashed in. Part of government semi-acknowledges the dangers of climate change, other parts are either oblivious or unable, as you say, to get their heads around the implications.

When I said “Let’s hope so” I was thinking more of anything that will prevent the projects getting off the ground, not welcoming the disintegration of the global economy. I should have made that a bit clearer. I’ve got a review copy of Paul Gilding’s The Great Disruption arriving soon in which he apparently places climate change in the context of wider collapse. “Stark and unflinching” according to the blurb, but also “deeply optimistic”. It’ll be interesting to see how he manages that spectrum.